With the release of J/Link, almost all the capabilities of Java are now available directly from Mathematica. Now you can perform many tasks that used to require writing a MathLink program by simply loading the appropriate classes.

Communication with the serial port in Java is handled by a standard extension package for Java called javax.comm, otherwise known as the Java Communications API. This functionality is not yet part of the standard Java 2 platform, although it is a standard extension. Implementations are freely available for Solaris, Windows, and various Unix platforms. Most other platforms will soon be supported.

To use J/Link to control a serial port, all you need to do is use the classes and methods that are available from the Java Communications API. Note that J/Link neither has nor requires any special knowledge about these Java classes. It works this way with any Java class.